Cannabis-induced psychosis:: a cross-sectional comparison with acute schizophrenia

Objective: The existence of cannabis-induced psychosis (CP) remains controversial, partly because of methodological problems. We hypothesize that acute schizophrenia (AS) and CP can have distinct demographic, premorbid and clinical features. Method: We compared 26 patients with CP to 35 with AS, after their cannabis-consumption status was confirmed by repeated urine screens. Patients with CP were assessed after at least I week but not more than I month of abstinence. Symptoms were evaluated with the Present State Examination (PSE). Results: In group CP, male gender, expansive mood and ideation, derealization/depersonalization, visual hallucinations, and disturbances of sensorium were more frequent than in group AS. Premorbid schizoid personality traits were more frequently associated to AS and antisocial personality traits to CP. Conclusion: The continuous heavy use of cannabis can induce a psychotic disorder distinct from AS. These two clinical entities share some features but they differ in others.